Method of forming a decorative foamed resin speaker cover

ABSTRACT

A decorative speaker cover and a method for fabricating a speaker cover for use in a ceiling or wall comprising panels, the speaker cover having an appearance which blends with other panels so that it conceals the presence of a speaker system while providing satisfactory transmission of sound from the speaker system. The decorative speaker cover is fabricated by first forming a mold liner suitable for generating a facsimile of a ceiling or wall panel. Next, the mold liner is placed in a molding container and a closed cell expandable foam system is uniformly spread over the mold liner so that the foam rises vertically. The thickness of the resulting cast is reduced to a dimension below which acoustic transmission loss is not discernable by human ears.

FIELD OF THE INVENTION

This invention relates to loudspeaker systems and, more particularly,deals with a novel decorative speaker cover for concealing a loudspeakersystem.

BACKGROUND OF THE INVENTION

In the past, loudspeaker covers for walls and ceilings have beencomprised of fabric stretched over a planar form. These covers normallydo not enhance the aesthetic appearance of walls and ceilings andoccasionally the resulting interruption of ornate patterns degrades thebeauty of ceiling or wall designs. In order to overcome this problem asuitable speaker cover must be aesthetically similar to the wall orceiling finish as well as being acoustically transparent so as not tonoticeably affect sound radiated by the speaker system. In particular,there has been an interest in decorating restaurants and the like withartistic relief forms in the ceilings. For example, ceilings whichcomprise ornate metallic panels are becoming popular in restaurants andother commercial establishments to give the appearance of the late 19thand early 20th century. Moreover, even in rooms having modern modulardrop ceilings or untextured wall panels, it is sometimes desirable toconceal the presence of a speaker system. Heretofore there has not beenknown a method for making low uniform density, acoustically transparentspeaker covers which replicate ceiling and wall designs. Accordingly,there exits a need for decorative speaker covers which provide effectivesound transmission for loudspeakers and yet so perfectly blend with thewall or ceiling surface that there is no visible evidence that a speakercover is present.

SUMMARY OF THE INVENTION

The present invention has been developed for the purpose of obviatingthe aforesaid disadvantages of the prior art. Accordingly, the inventionhas as its most general object the provision of an acousticallytransparent speaker cover which blends in with a wall or ceiling so asto disguise its presence. In one embodiment, the invention has as itsfurther object the provision of a speaker cover having an artisticrelief pattern similar to the surface of relief panels in ceilings orwalls so as to maintain the ornamental shape and design of the surface.

Among the several objects of the present invention may also be noted theprovision of a method for forming a speaker cover by replicating aceiling or wall panel which replica when placed in a ceiling or wall hasthe identical visual appearance as the original panel but which differsfrom the original because it has a predetermined thickness and a low anduniform density which render the replica suitable for acoustictransmission in a speaker system; and the provision of a method forspreading a closed cell foam system in order to fabricate a panel havinga low and uniform density, the panel being useful as a speaker coverwhich overcomes the above discussed limitations of fabric speaker coversknown in the prior art.

Fabrication of a speaker cover with a particular relief design isaccomplished generally by forming a mold liner of the ornamental shapeand design. This may be accomplished by pouring a molding compound overa relief panel of the ceiling or wall. The liner is removed from thepanel and placed in a mold. Closed cell foam is spread evenly over themold and allowed to rise. A press is next placed over the foamapproximately one inch above the molding surface to restrict the foamheight. The excess foam is allowed to pour out the sides of the pressingapparatus. The foam is allowed to cure for an appropriate length oftime. The cast is removed from the mold and the thickness is reduced byshaving or sanding. The resulting decorative speaker panel conforms tothe exact ornamental shape and design of the ceiling or wall panel. Itis comprised of closed cells in order to minimize density thus avoidingattenuation in acoustic transmission. The cast is sufficiently strong tosupport the load of a commercial speaker and yet thin enough to beadhesively attached to the diaphragm of a hemispherically radiatingspeaker system.

Other features and advantages of the present invention will becomeapparent from the following detailed description, taken in conjunctionwith the accompanying drawings, which illustrate, by way of example, theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a decorative speaker cover embodying thepresent invention and is illustrated as mounted on the front of aloudspeaker;

FIG. 2 represents the rear view of the loudspeaker showing theconstruction of the back of a loudspeaker system suitable for use withthe inventive speaker cover;

FIG. 3 is a side view of a loudspeaker system having the inventivespeaker cover mounted on the front planar surface of the loudspeaker;

FIG. 4 illustrates a mold used to form the decorative speaker cover;

FIG. 5 shows disbursement or "wetting out" of the mold surface by theyet unexpanded foam medium over the entire surface of the mold linerachieved by tilting of the mold container;

FIG. 6 illustrates placement of a mold container under a press;

FIG. 7 shows a foam casting medium expanding over a mold; and

FIG. 8 shows the process of removing a rubber mold from the inventivespeaker cover.

DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT

As shown in the exemplary drawings, the present invention includes adecorative speaker cover and a method of making the decorative speakercover. In a preferred embodiment, the speaker cover is molded in reliefto match the corresponding appearance of an existing ceiling or wallpanel. In use, it may be dropped directly into a T-bar type of suspendedceiling system or otherwise affixed to ceiling support members. Withreference to the figures generally the cover is made by first forming amold liner 26 from a panel to be duplicated by pouring a moldingcompound, such as, for example, silicone rubber, over the panel within asuitable form. After curing and removing from the form, the liner 26 isthen placed in the bottom of a press on a hard surface. A closed cellfoam in liquid form, such as, for example, a polyurethane foam, isspread over the entire mold surface and allowed to expand vertically asit cures. A press, i.e., a large flat plate, is placed a predetermineddistance above the surface of the mold liner 26 to restrict the verticalexpansion of the foam in order to control its density. Some foam escapeslaterally from between the press and mold liner. The foam is allowed tocure and speaker cover 10 in relief is removed from the mold. Thethickness of the speaker cover is then reduced to less than 0.7 cm byeither shaving or sanding in order to form a thin sheet of apredetermined thickness. The resulting speaker cover matches theduplicated panel and may be glued onto the front surface of a speakerfor concealing the speaker in a drop ceiling or panelled wall. Othermethods well known in the art may be used to place the speaker systemand cover in walls and ceilings which have ornate relief patterns.

By way of example, the speaker cover indicated generally by reference 10in FIG. 1 is shown mounted on the diaphragm of a hemisphericallyradiating speaker system 12. The speaker cover 10 is formed in relief tomatch existing panels in the ceiling in which the speaker system is tobe installed. The speaker system generally indicated as 12 in FIGS. 1, 2and 3 may illustratively take the form of a BESC70D loudspeaker system,manufactured by B.E.S. Commercial Sound Products Division under theirdesignation C70D and suitable for installation in a drop ceiling having"T" bar construction.

In the preferred embodiment, the speaker cover 10 is mounted on thesurface of a planar diaphragm 14 with an adhesive bond along the edgesof the contacting surfaces. Because speaker cover 10 is in physicalcontact with diaphragm 14 it radiates the acoustic vibrations generatedin the diaphragm. The low density of the speaker cover assures that thefrequency response of this radiating cover is consistent with thefrequencies generated in the diaphragm. The inventor has discovered thatsuitable densities for the speaker cover range from approximately 1.9 to2.2 lbs. per cubic foot. For a 23"×23" panel the overall weight shoulddesirably be approximately 11 ounces.

Referring to FIG. 2 there is shown the back view of the loudspeakersystem as described previously. An aluminum frame 16 supports the planarspeaker diaphragm 14 and two independent magnetic circuits 20 and 22. Inthe preferred embodiment, this loudspeaker system fits into a standardTbar frame for suspended ceiling systems having dimensions approximately23 inches in length, 23 inches in width and 3 inches in depth.

Referring now to FIG. 3 there is shown a side view of speaker system 12having speaker cover 10 adhesively attached to the front surface of theplanar diaphragm 14 of the loudspeaker system. The speaker cover, formedin relief to match an existing panel, is attached along the edges 15 ofplanar diaphragm 14 using an appropriate adhesive such as a latex glue.The adhesive selected should be of a type which does not corrode thematerial of either the cover 10 or the speaker diaphragm 14. Solventglues can be used if the mating surfaces are protected by non-sensitivecoverings such as a latex paint. When placed in a ceiling or wall thefront surface of speaker cover 10 replicates the ornamental shape anddesign of existing panels.

A method for making a relief speaker cover which duplicates theappearance of a panel is now described in detail. First, a panel to beduplicated is used to form a mold. Silicone rubber or another suitablemolding compound is poured over the panel and allowed to dry completely,i.e., to cure. This results in a mold liner having a mirror image of theornamental design and shape of the panel surface.

Referring to FIG. 4, mold liner 26 is placed in molding container 24. Apredetermined amount of closed cell low density pour foam material suchas a system based on polymeric isocyanate is then poured onto the moldliner. As illustrated in FIG. 5, mold container 24 is pivotally mountedon a gimbal (not shown) so that the foam may be evenly spread over moldliner 26 by tilting the mold container about the gimbal. This method ofspreading of the liquid foam has been found necessary for controllingthe uniform density of the finished panel. If the foam is allowed toexpand along the mold liner surface, friction at the foam/linerinterface causes collapse of many of the cells. So long as the entiresurface of mold liner 26 is wetted with foam that has undergone minimalexpansion, expansion is limited to a vertical direction above the moldliner. Otherwise, with expansion occurring along the mold surface, thedistribution of foam cells becomes uneven and a substantial number ofcells break open forming a dense skin on the relief surface. With theexpansion occurring normal to the relief surface, the finished speakercover accurately replicates the indentations and contours of the moldliner and has a uniform density.

Referring next to FIG. 6, the mold container 24 is positioned underneathpress 28 immediately after spreading of the liquid foam material. As thefoam expands, it presses up against the bottom surface of press 28 andflows over the edges of the mold container 24.

Referring to FIG. 7 there is shown foam 30 expanding normal to thesurface of mold liner 26. The press 28 is placed a predetermineddistance from the surface of the design mold liner 26. As foam 30expands it eventually contacts the bottom surface of press 28 and flowsover the sides of the molding container 24. By adjusting the height ofpress 28 the density and weight of foam 30 can be controlled. Forinstance, if press 28 is moved further away from mold liner 26 a givenamount of liquid foam will result in a panel which is relatively thickand of low density mass per unit volume. Moving press 28 closer to thesurface of design mold 26 restricts the escape of foam, thus causing thedensity of foam 30 to increase and the thickness of the resulting panelto decrease. Once foam 30 cures, the resulting panel 32 and rubber mold26 are removed from the press.

Referring to FIG. 8 there is shown the process of removing the rubbermold liner 26 from the formed panel 32. Panel 32 is then cut and shapedto the desired thickness and length and width. The thin panel is coloredto match the wall or ceiling design and is then adhesively attached asdescribed above by an appropriate adhesive to the front planar surfaceof the loudspeaker system. It is noted that while attachment of thecover to the surface of the loudspeaker system is often preferred, it isnot essential to the invention. Furthermore, if the finished panel is auniform color, such color may be mixed into the liquid foam material.

Thus there has been shown a decorative speaker cover and a method ofmaking the same in which the speaker cover includes the exact ornamentalshape and design of a ceiling or wall panel. It is understood that thedesign of the inventive speaker cover can replicate any ornamentalpattern and may form an integral part of a pattern, design or imagewhich is greater in size than the speaker cover dimensions. Theinventive cover may also be painted, dyed or otherwise colored to blendwith other panels.

The speaker cover hides the front surface of a loudspeaker system whichis placed in a ceiling or wall. While minimizing the loss of acousticenergy transmitted through the cover the inventive foam speaker coveralso serves as a medium for replicating designs, textures, reliefpatterns and other visual images thus simulating wall or ceiling panelsfabricated out of metal, fiberboard and other building materials.Several particular forms of the invention have been illustrated anddescribed, but it will also be apparent that various modifications canbe made without departing from the spirit and scope of the invention.

We claim:
 1. A method of forming a decorative speaker cover to be placedin a ceiling or wall comprising an array of panels wherein the panelscontain an ornamental relief, the method comprising the steps of:(a)forming a mold liner having a surface duplicating a ceiling panel'sornamental relief; (b) placing the mold liner into a molding containerhaving a pedetermined height measured from a plane of the mold linersurface; (c) pouring a closed cell expandable foam into the moldingcontainer and spreading it over the mold liner so that indentations inthe mold liner corresponding to the ornamental relief are filled withfoam in order to form a cast of the ornamental relief; (d) allowing thefoam to rise vertically above the height of the molding container inorder to control the density of the cast; and (e) trimming the cast toreduce its thickness to a dimension having an acoustic transmission lossnot discernible by human ears.
 2. The method of claim 1 furthercomprising the steps of tilting the mold container about a center axisimmediately after the foam is poured so that the mold liner is wettedwith foam which has undergone minimal expansion.
 3. The method of claim1 further comprising the step of:using a press with an adjustable heightover the mold in order to control the escape of foam and the resultingthickness of the cast.
 4. The method of claim 1 further comprising thestep of coloring the relief surface of the cast in order to match aceiling or wall.